1. Field of the Invention
The invention relates to an actuator and an actuator cover structure attached to the outside of a vehicular power transmitting apparatus, and that power transmitting apparatus.
2. Description of the Related Art
A vehicular automatic transmission or a power transmitting apparatus for a hybrid vehicle that has both an internal combustion engine and an electric motor as prime movers, is known which increases the degree of freedom in the arrangement and operating method of a shift operating portion by replacing mechanically operated linkage with an electrically operated system using so-called shift-by-wire (hereinafter simply referred to as “SBW”) control which electrically detects operation of a shift lever or a shift switch and controls range shifting means with an actuator that can be electrically controlled. This kind of power transmitting apparatus includes a parking lock mechanism that mechanically locks any one rotating member in a power transmitting path from the prime mover to driving wheels when a shift lever is shifted into a parking range position.
Japanese Patent No. 3692791, for example, describes one such parking lock mechanism that includes, for example, a pivoting lock pawl that engages/disengages to/from any one rotating member in the power transmitting path from the prime mover to the driving wheels, a translation cam that makes the lock pawl pivot, an operating link that moves the translation cam backward or forward, and an SBW motor that turns the operating link.
However, in a power transmitting apparatus having a parking mechanism like that described above, part of the motor case of the SBW motor which is an actuator that is mounted to the outside of the transmission case is made of resin to reduce the weight. As a result, a flange portion in particular, which is used to fasten the resin cover to the main body of the motor case, is not strong enough to withstand intentional damage. As a result, the vehicle could conceivably be stolen by breaking the flange portion (i.e., cracking the resin of the fastening portion using a screwdriver and a hammer, for example), removing the resin cover, and turning the rotor of the SBW motor to unlock the parking lock mechanism so that the vehicle can be moved.
Although it is possible to make the entire resin cover portion of the motor case out of metal in order to prevent this type of theft, doing so would also greatly increase the weight of the actuator which would reduce fuel efficiency.